Signal system



Feb. 28 1.933. 1 LYNN 1,899,580

S IGNAL SYSTEM Filed Nov. 4, 1929 Inventor:

Lambert H. Lynn,

b MM

His Attorney Patented Feb. 28, 1933 vireo STATES PATENT OFFICE LAMBERT H. LYNN, 0F SCHENECTADY, NEW YORK, 'ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK SIGNAL SYSTEM Application filedflo'vembere, 1929. Serial No. 404,722.

My invention relates to signal systems and more particularly'to signal systems employing electron discharge devices. 1

It frequently becomes desirable in the use of systems of the type indicated, to connect an electron discharge amplifier employing a single discharge device in the last stage to supply oscillations to an additional amplifier of push pull type or to other forms of balanced load circuits.

One of the objects of my inventionis to provide improved means whereby this result may be efiected. A

A further object of my invention is to provide means whereby the potential on opposite sides of the load circuit of an electron discharge device employed as an amplifier is maintained in balanced relation with respect to the cathode. Thus, additional discharge devices such as those of a balanced, or push pull amplifier, may be connected between the cathode and the opposite points on the load circuit and hence receive therefrom equal potentials which are in opposite phase. In addition thereto the cathodes of all of the discharge devices may be maintained at a like potential and supplied from the same source.

Afurther object of my invention is to provide means such that when the coupling between amplifiers of the type mentioned comprises a tuned circuit, the tendency'of parasitic oscillations to be set up in the tuned circuit due to unbalanced impedances between the opposite sides of the tuned circuit and the cathode, resulting from inherent impedance of the discharge device, is avoided.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing in which the single figure represents an embodi-l ment of my invention. I

Referring to the drawing, I have shown at 1 an electron discharge amplifier which 1s connected to supply high frequency oscillation to the grid of apair of push pull connected amplifiers 2 and 3. Connected be- I tween the anod'e and the cathode of the -.dis-.

charge device 1; is a tuned circuit-4 comprising inductance and a capacitance 6. The cathodes of all of'the discharge devicesare maintained at ground potential and are connected to be supplied froma single source of electromotive force, this source comprising cathode heating transformer 7. An intermediate point on the tuned circuit' l is similarly connected to the cathode, as indicated by theground connection-shown thereon. Opposite points on the inductance are connected through coupling condensers 8 and 9 to the grids of the discharge devices, 2 and.

3, respectively. Positive potential is supplied to the anode of the discharge device 1 through a circuit extending through the source of anode potential 10 toja mid-point on the inductance 5, the upper terminal .of which is connected to the anode. Positivef potential is also supplied from the source 10 through a conductor 11 and an additional source of potential 12 to the anode of the push pull amplifiers 2 and 3, this connection being made to the midpoint on the primary winding of the output transformer 13. The usual sources of biasing potential 14 and 15 are connected between the cathode ofthe respective amplifiers 1, 2 and 3 and the grids thereof, these connections being completed through the usual grid-leak resistances and grid ine ductance.

In operation oscillations are suppliedthrough input transformer '17 to the grid of I discharge devicel thereby to control the impedance of the discharge device. These ossillations are then excited, or repeated, in the tuned circuit 4, amplifiedby devices 2 and 3 and supplied to any desired outputrcircuit through transformer 13. The output circuits 7 of devices 2 and 3 may of course be tuned to the same frequency ple thereof as desired.

Referring now to the tuned circuit 4: whlch as circuit 4 or a multicomprises the load circuit of the amplifier 1, the ground connection referred to is made up-- on the'capacitance 6. Thiscapacitancemay comprise apair of condensers the movable the upper p'or L i is conncceen .o

QED

electron disclia type such th has less el'lect, but

is case an by-pass condenser 15 is connected a f; i.

the discharge device.

discharge device. lllhusthe ci screen grid and the cat denser has tie same cite-c.

circuit as he inherent CQQLC'E anode and cahode and, Illl'iElC-p. is cliectivay L connected bet. een the anode and may be treated though it were 1..

The o: pacitance will a er he more fully understood. For the pur e o t; the uncle sir-able effects 0 16 is inserted Cult 4; Miis condens it just balances the e posite side of the tuned circuitode including the inherent .cli that r then oscillzne freely a frequency and in balanced 1Gl21t1"--1 w 'pect to the cathode. The grids c; rge devices circuit oscillations of equal 2 and 3,the cathodes or which are connect er. with the cathode of device '1, may then be connected through their res ective coupling condensers 8 and 9 to onpositepoints on inductance 5 and hence receive from the timed magnitude and iiiers 2 and 1 may of opposite phase. Thus the 3 may then operate in balanced relat on and assume equal portions of the 1 It will now be ajoparc? a capacity between the anon-e and cat the discharge de v electron discliarc'c derice is employed a d this capaci;y, i additionto thcrcanacity where a screened grin QlEQLl'Oll discharge device is employed, is eil'ectivelr in shunt with the upper portion of the ca itance \5. The efi ectoi this, were conde er 16 not ins in the circuit, is to of the circuit somewhat ditierent ies set up in the opposite bra circuit. V hil these parasitic oscill 1' notlikely to be particularly harmful the tuned circuit is adjusted to oscillate at: iectively disconnected from said grid except ent tuned cir-.

under load circ an electron discharge device in be'employee and, further, oscillations from this lead ircuit l fer'ent types of circi beyond the circuit l.

of course, contemplate by the appended claims to coyer any such modifications of the arrangement shown as fall within the true spirit and scope of my invention.

l'fhat I claim as new and desire to secure combination, an electron discharge device having a grid, an anode, and a cathode,

a load circuit connected between said anode v l l lode, a connection between an interpoint on said load clrcuit ans-said and means for maintaining the pocathode, and means connected between one side of said tuned circuit and the cathode to balance the impedance between the opposite side of said tuned circuit and said cathode,

ii 1 side of said tuned circuit being efiecti ely' disconnected from said grid except through said anode and cathode.

V 3, In combinationfla pair of electron dis- .levices connected in push pull relation, an input circuit connected between the grids of said discharge devices, an additional electron discharge device having an anode and a cathode connected respectively to one side and an intermediate point on said circuit, and a grid. 0. connection between the cathodes of all of said discharge devices and the mi d-point on said circuit, and impedance means connected between the ca .hodc and the side of said circuit opposite said anode, said opposite side of said tuned circuit being efr- A lsher means or balancing the through said anode and said cathode for causing the oscillations supplied by said circuit to said push pull electron discharge devices to be balanced with respect to said cathodes.

4. In combination, a pair of electron discharge devices connected in push pull relation, an input circuit connected between the grids of said discharge devices, an additional electron discharge device having an anode and a cathode connected respectively to one side and an intermediate point on said input circuit, and a grid, a connection between the cathodes of all of said discharge devices and a mid-point on said input circuit, and a condenser included in the connection between the cathode or" said additional discharge device andthe side of said tuned circuit opposite said anode, said condenser having capacity substantially equal to the effective capacity between the anode and the cathode of the discharge device, and said side of said tuned circuit to which said condenser is connected being effectively disconnected from said grid.

5. In combination, an electron discharge device having an anode, and a cathode, an output circuit having opposite sides balanced with respect to ground, a tuned circuit com prising shunt connected inductance and capacity, the sides of said output circuit being connected to opposite points on said tuned circuit, a source of electroinotive force connected between said cathode'and an intermediate point on said inductance, a connection between the midpoint on said capacitance and ground, a connection from one side of the tuned circuit to said anode and a condenser connected between the opposite side of said tuned circuit and ground, said condenser being of such value that the opposite sides of the tuned circuit are balanced with respect to ground and a parasitic path is produced from the cathode to the midpoint of said tuned circuit having impedance equal to the impedance of the opposite correspond- 111g path including the anode of the discharge device.

6. In combination, an electron discharge e to points on said tun-ed circuit equally and oppositely spaced from said midpoint, said last mentioned condenser having a value substantially equal to the effective capacitance between said anode and cathode, said effective capacitance including the capacitance of said first mentioned condenser.

' 7 In combination, a pair of electron discharge devices connected in push pull relation, each of said discharge devices having I its midpoint connected to said cathode, said first mentioned condenser having capacitance equal to the efiective capacitance between said anode and cathode whereby said opposite points may be maintained in balance relation with respect to said cathode.

In witness whereof, I have hereunto set my hand this 1st day of November, 1929.

LAMBERT H. LYNN. 

